A British court has disclosed that an Islamic State-linked extremist has pleaded guilty to five offenses after being found with incriminating information stored in a cuff link.

Samata Ullah had a USB-equipped cufflink with a Linux operating system loaded onto it that was used to store extremist data, including a blog.

He pleaded guilty earlier this month at the Old Bailey courthouse to five offenses including possession of an article for terrorist purposes. The court withheld the information until Monday for legal reasons.

The 34-year-old from Wales was arrested in September and admitted ties to the so-called Islamic State group. He was found to have provided instructional videos on how to protect sensitive data and remain anonymous online through encryption programs.